Luminescence studies on Dy3+ and Dy3+:Eu3+ co-doped boro-phosphate glasses for WLED applications

Abstract

Dy3+ and Dy3+:Eu3+ co-doped boro-phosphate glasses have been prepared and optically characterized using absorption, luminescence and decay measurements. The Nephelauxetic ratios (β), Bonding parameters (δ) and Judd-Ofelt (JO) intensity parameters Ωλ (λ = 2, 4 and 6) were calculated to study the nature of the environment around the RE3+ ions in the prepared glasses. The yellow to blue (Y/B) intensity ratio and the chromaticity color coordinates were calculated from the luminescence measurements. The lifetimes of the 4F9/2 excited level were measured using decay curves and is found to decrease in the Dy3+:Eu3+ co-doped glass due to the occurrence of resonant energy transfer between Dy3+–Eu3+ ions and the non-exponential decay rates have been fitted with Inokuti–Hirayama (IH) model. The decay curves are well fitted for S= 6 suggesting that the interaction between active ions for the energy transfer is of dipole-dipole nature.